JPH10270931A - Antenna for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the sensitivity of a first frequency band by prolonging the valid length of a first antenna conductor with the sum of the conductor length of the first antenna conductor and that of a second antenna conductor to receive a first frequency band at the time of receiving it. SOLUTION: A signal received by a first antenna conductor AT1 is inputted to a receiver 20 through a coaxial cable 10 from a circuit 9 through a first connection line 6. A first coil L1 is connected between the first antenna conductor AT1 and the second antenna conductor AT2 and it has an inductance value becoming high impedance for attenuating the reception signal of the second frequency band. Thus, the first antenna conductor AT1 is insulated from the second antenna conductor AT2 and the deterioration of the sensitivity of the second frequency band is prevented at the time of receiving the second frequency band. At the time of diversity reception, a lead line 11 and the coaxial cable 13 are provided, a stronger reception signal in the reception signals of the first antenna conductor AT1 and the second antenna conductor AT2 is selected and it is inputted to the receiver 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular antenna suitable for receiving AM broadcasts, FM broadcasts, TV broadcasts and the like, and particularly suitable for providing an antenna conductor on a rear side window glass plate of an automobile.

[0002]

2. Description of the Related Art In a conventional glass antenna for a vehicle for receiving AM broadcast, FM broadcast, TV broadcast, etc., an antenna conductor AT is provided on a rear left side window glass plate 1a of an automobile as shown in FIG. The point 4a and the circuit 9 are connected via a first connection line 6, and further, the first connection line 6 and the receiver 20 are connected via a coaxial cable 10, and the power supply point 4a
And the receiver 20 were connected. The circuit 9 is usually a preamplifier, an impedance matching circuit or a resonance circuit.

[0003]

However, although the conventional glass antenna for a vehicle shown in FIG. 2 is compact, the sensitivity is insufficient when receiving an AM broadcast band, and AM broadcast cannot be satisfactorily received in an area where radio waves are weak. There was a problem. The reason for the lack of sensitivity is that the wavelength of the radio wave in the AM broadcast band is about 1
This is because the conductor length of the antenna conductor AT provided on the window glass plate having a small area compared to this wavelength is as long as 85 m to 575 m. Therefore, it is desirable to develop an antenna that can be provided on a window glass plate having a small area, can achieve compactness, can obtain sufficient AM broadcast band sensitivity, and can simultaneously receive the FM broadcast band. Was rare.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a first frequency band and a first frequency band.
A second antenna having a frequency higher than that of the first antenna conductor.
Antenna conductor and a first coil are provided in the vehicle, and a feed point of the first antenna conductor is connected to one end of the first coil, and a feed point of the second antenna conductor is connected to the other end of the first coil. And the first coil has an inductance value such that the impedance is high in the second frequency band, and the first coil has a connection line connecting the feeding point of the first antenna conductor and one end of the first coil. A vehicle wherein the length is shortened so as not to attenuate a received signal in a second frequency band received by the first antenna conductor, and a received signal at a feed point of the first antenna conductor is input to a receiver. Provide an antenna for use.

[0005] A vehicle antenna for receiving a first frequency band and a second frequency band higher in frequency than the first frequency band, comprising a first antenna conductor, a second antenna conductor, and a second antenna. One coil is provided in the vehicle, and connects a feeding point of the first antenna conductor to one end of the first coil;
And the other end of the second coil is connected to one end of the second coil.
The other end of the coil and the feeding point of the second antenna conductor are connected, and both the first coil and the second coil have an inductance value such that the impedance becomes high in the second frequency band. The length of the connection line connecting the feeding point of the first antenna conductor and one end of the first coil is shortened so as not to attenuate the received signal of the second frequency band received by the first antenna conductor, A vehicle antenna for selecting the stronger one of the received signal at the feed point of the antenna conductor and the received signal at the feed point of the second antenna conductor and inputting the selected signal to the receiver.

In addition, the feeding point of the first antenna conductor and the first antenna
The length of a connection line connecting one end of the coil is 40 cm or less. In addition, the present invention provides the above vehicle antenna, wherein the first antenna conductor is provided on the rear left side window glass plate, and the second antenna conductor is provided on the rear right side window glass plate.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention aims at receiving two or more frequency bands. The frequency of the second frequency band according to the present invention is higher than the frequency of the first frequency band according to the present invention. As a typical example, for example, there is a case where the first frequency band is an AM broadcast band and the second frequency band is an FM broadcast band.

Further, it is necessary that the vehicle be provided with two or more antenna conductors. This is because two or more antenna conductors are connected at a high frequency in the first frequency band, and the effective length of the first antenna conductor is substantially increased to improve the sensitivity in the first frequency band. Therefore, when receiving the first frequency band, it is necessary to lengthen the effective length of the first antenna conductor by the sum of the conductor length of the first antenna conductor and the conductor length of the second antenna conductor. Become.

[0009] When receiving the second frequency band, the signal is received substantially only by the conductor length of the first antenna conductor. Therefore, it is preferable that the specifications such as the conductor length and the shape of the first antenna conductor be suitable for reception in the second frequency band.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a typical example of a vehicle antenna according to the present invention. In FIG. 1, 1b is a rear right side window glass plate,
AT ₁ the first antenna conductor, AT ₂ is the second antenna conductor, 4b second feed point, L ₁ is a first coil, L ₂
Is a second coil, 6 is a first connection line, 8 is a second connection line, 11 is a lead wire, and 13 is a second coaxial cable. The second coil L ₂ , the circuit 9, the lead wire 11 and the coaxial cable 13 are provided as needed, and in other drawings, they are provided as needed.

The received signal received by the first antenna conductor AT ₁ is sent to the circuit 9 via the first connection line 6 and is input to the receiver 20 via the coaxial cable 10. First
Coil L ₁ of is connected between the first antenna conductor AT ₁ and the second antenna conductor AT _2, it has an inductance value as a high impedance, such as to attenuate the received signal in the second frequency band. When receiving the second frequency band,
The first antenna conductor AT _{1 is connected} to the second antenna conductor AT ₂
This is to prevent the sensitivity of the second frequency band from being lowered by insulating the same.

[0012] It is preferable that the second coil L ₂ is provided. Upon receipt of the second frequency band, it is to prevent the sensitivity of the second frequency band as completely as possible the insulation of the first antenna conductor AT ₁ and the second antenna conductor AT ₂ is reduced. The first coil L ₁ and the second coil L ₂ that connect a plurality of antenna conductors are hereinafter referred to as connection coils. Third to eighth coils described later are also connection coils.

The inductance of the _first coil L ₁ , the second
The high impedance at the inductance of the coil L _2, typically refers to about 5 times greater than the input impedance of the receiver. When the second frequency band is, for example, an FM broadcast band, the input impedance on the receiver side when receiving the FM broadcast is usually 50 or 75Ω. Therefore, for example, when the input impedance on the receiver side is 50Ω, high impedance is 250Ω or more.

It is preferable that the connection length between the feeding point of the first antenna conductor and one end of the first coil is shortened so as not to attenuate the received signal in the second frequency band. In particular,
It is preferable length of the first connecting line 6 for connecting the first feeding point 4a of the antenna conductor AT ₁ and a first one end of the coil L ₁ is equal to or less than 40 cm. This is because the sensitivity in the second frequency band decreases.

When the distance is 40 cm or less, the sensitivity in the entire second frequency band is usually improved by 2 to 3 dB or more as compared with the case where the distance is more than 40 cm. A more preferred range is 20
cm or less, 20 cm if it is 20 cm or less
The sensitivity over the entire second frequency band,
Usually, it is improved by 1 to 2 dB or more.

[0016] The first end of the coil L _1, the winding-start or shall refer to the portion of the winding end, a first connecting line 6, the windings of the connection coil and a second connecting line 8 To integrally In this case, the end of the connection coil refers to the start or end of winding. The same applies to other connection coils.

In FIG. 1, when performing diversity reception, a lead wire 11 and a coaxial cable 13 are provided. During diversity reception, of the first antenna conductor AT ₁ of the received signal and the second received signal of the antenna conductor AT _2, received selected by the selection circuit stronger machine 2
0 is input. Figure 1 for diversity reception
Has a selection circuit. However, the present invention is not limited to this, and the receiver 20 may not include the selection circuit, and the receiver 20 and the selection circuit may be separated.

The length of the second antenna conductor AT ₂ feeding point 4b and a second connecting line that connects the one end of the coil L ₂ is 4
It is preferably 0 cm or less, more preferably 20 cm or less. For the same reason as described above for the length of the first connection line 6.

FIG. 3 is a block diagram showing another example of a vehicle antenna according to the present invention, which is different from FIG. In FIG. 3, 3 is a glass plate of the rear window of the vehicle, 22 is a heater wire, 25a, 25
b is a bus bar, 29 is a choke coil, 30 is a DC power supply,
21 is a noise cut capacitor, 12a and 12b are high frequency choke coils, and 41 is a DC blocking capacitor.

In the vehicle antenna of the present invention shown in FIG.
The defogger composed of the heater wire 22 and the bus bars 25a and 25b functions as an antenna, and corresponds to the _second antenna conductor AT2 in FIG. Performing diversity reception between the first antenna conductor AT ₁ and the defogger.

In FIG. 3, the choke coil 2 is connected between the bus bars 25a, 25b and the DC power supply 30 for defogger.
9 and high-frequency choke coils 12a, 12b,
By increasing the impedance of the choke coil 29 and the high-frequency choke coils 12a and 12b in the high-frequency band, a DC current flows from the DC power supply 30 to the defogger, but a current in a high-frequency band such as a broadcast band is cut off.

In this manner, the choke coil 29 and the high-frequency choke coils 12a and 12b can insulate the heater wire 22 of the defogger and the bus bars 25a and 25b from the vehicle body at high frequency.
It is possible to prevent a reception current in a high-frequency band such as a radio broadcast band induced by a and 25b from flowing to the vehicle body ground, and to transmit the reception current to the receiver 30 without leakage.

Also, the first frequency band is a medium wave band, for example,
When the AM broadcast band is used, the second frequency band is the FM broadcast band, and when only the AM broadcast band is received using the defogger, the high-frequency choke coils 12a and 12b are:
Usually, it is unnecessary, and only the choke coil 29 is sufficient.
If only the M broadcast band is to be received, only the high-frequency choke coils 12a and 12b may be used.

Also, even in the case of receiving both the medium wave band and the FM broadcast band, if there is a coil that satisfies both functions of the choke coil 29 and the high frequency choke coils 12a and 12b, only such a coil is sufficient. .

FIG. 4 is a block diagram showing another example of a vehicle antenna according to the present invention, which is different from those shown in FIGS. Upon receipt of a first frequency band, by connecting the first antenna conductor AT ₁ and the defogger, by increasing the effective length of the first antenna conductor, a first antenna conductor AT ₁ and the second antenna performing diversity reception with the conductor aT _2.

In the vehicle antenna shown in FIG. 4, an antenna conductor such as a first antenna conductor may be used instead of the defogger. Also, connect the bus bar 25a and the receiver 30, the first antenna conductor AT _1, may be carried out diversity reception among three parties of the second antenna conductor AT ₂ and the bus bar 25a.

In FIG. 4, the first antenna conductor AT ₁
When the second antenna conductor AT ₂ is provided in a separate window glass sheet. However, the first antenna conductor AT ₁ and the second antenna conductor AT ₁
And the antenna conductor AT ₂ may be provided on the same window glass sheet.

FIG. 5 is a block diagram of an example of a vehicle antenna of the present invention of a different type from those shown in FIGS. 1, 3 and 4. In FIG. 5, AT ₃ is a third antenna conductor, AT ₄ is a fourth antenna conductor, L ₃ is a third coil, L ₄ is a fourth coil, L ₅ is a fifth coil, and L ₆ is a fourth coil. 6 of the coil, L ₇ is a coil of the 7, L ₈ is a coil of the eighth, the 4c third feed point of the antenna conductor AT _3, 4d fourth antenna conductor a
Feeding point T _4, 40 is a glass plate of the front window. In the vehicle antenna shown in FIG. 5 performs diversity reception among four parties of the first antenna conductor AT _1, second antenna conductor AT _2, a third antenna conductor AT ₃ and a fourth antenna conductor AT _4. The glass plate of the window provided with the first to fourth antenna conductors is not limited to FIG.

In the vehicle antenna shown in FIG.
The coil L ₅ , the sixth coil L ₆ and the connection line thereof, or the seventh coil L ₇ , the eighth coil L ₈ and the connection line thereof are provided as necessary.

In FIGS. 1, 3, 4, and 5, the antenna conductor is provided on a window glass plate of a vehicle. However, the location of the vehicle where the antenna conductor is provided is not particularly limited. However, for convenience of mounting and compactness, each antenna conductor is preferably provided on a window glass plate of a vehicle.
Further, a part of the plurality of antenna conductors may be provided on a window glass plate of the vehicle, and the remaining antenna conductor may be provided on a portion other than the window glass plate of the vehicle. Further, the antenna conductor may be a pole antenna or the like other than the glass antenna.

In the present invention, when the antenna conductor is provided on the window glass plate of the vehicle, the glass plate of such a window is not particularly limited, and the glass plate of the rear window, the glass plate of the side window, and the front window. Or a glass plate of a roof window, or a defogger may not be provided on a glass plate of a window provided with an antenna conductor.

In the case where the antenna conductor is provided on the window glass plate of the vehicle, the first antenna conductor is provided on the rear left window glass plate, and the second antenna conductor is provided on the rear right side window glass plate. Preferably. This is because the directivity is excellent.

In the present invention, the antenna conductor is A
The present invention is not limited to the M broadcast band (medium wave) and the FM broadcast band, and can be applied to a short wave broadcast band, a long wave broadcast band, a television VHF band, a television UHF band, a telephone, and the like.

[0034]

【Example】

(Examples 1 to 5) A vehicle antenna as shown in FIG. 1 was manufactured.
Circuit 9 was a preamplifier. No second coil L ₂ , lead wire 11 and coaxial cable 13 were provided. The dimensions of the rear side window glass plate 1a were approximately 400 mm in the vertical direction and 550 mm in the horizontal direction. Such that the AT ₁ conductor length of the first antenna conductor as a length suitable for the FM broadcast band receiver,
The length of the first antenna conductor AT ₁ in a substantially vertical direction antenna wire 300 mm, 450 m in length in the substantially lateral direction antenna line
m, the first inductance value of the coil L ₁ 2.7Myu
H, The input impedance of the receiver at the time of FM broadcast reception was 50Ω.

The first first 5cm length of the connecting line 6 for connecting the feeding point 4a of the antenna conductor AT ₁ and a first end of the coil _{L 1, 15cm, 30cm, 50cm} , 80c
FIG. 6 shows the result of measuring the sensitivity-reception frequency characteristics of the FM broadcast band as m. In FIG. 6, B: 5 cm (Example 1), C: 15 cm (Example 2), D: 30 cm (Example 3),
E: 50 cm (Example 4), F: 80 cm (Example 5) (Examples 1 to 3 are Examples, Examples 4 and 5 are Comparative Examples). Example 1
3 can also receive AM broadcasts satisfactorily.
The average sensitivity of the entire broadcast band has been improved by almost 3 dB.

Example 6 As a comparative example, a vehicle antenna as shown in FIG. 2 was manufactured. Rear side window glass sheet 1a, for the first antenna conductor AT _1, using the same as those used in Example 1. FIG. 6 (A) shows sensitivity of FM broadcasting band versus reception frequency characteristics, and FIG. 8 shows sensitivity of AM broadcasting band.
6 shows a reception frequency characteristic.

Example 7 A vehicle antenna as shown in FIG. 3 was manufactured. The rear side window glass plate 1a used was the one on the left side of the vehicle, and was the same as in Example 1. The dimensions of the rear window glass plate 3 were approximately 450 mm in the vertical direction and 1200 mm in the horizontal direction. The length of the second connection line 8 was 400 mm, and the length of the first connection line 6 was 15 cm. FIG. 7 shows sensitivity-reception frequency characteristics of the AM broadcast band of Example 7.

The circuit constant of Example 7 is the first coil L
₁ = 2.7 μH, second coil L ₂ = 2.7 μH, capacitor 41 = 20 pF, choke coil 29 = ₁ mH,
The high-frequency choke coil 12a = 1 μH and the high-frequency choke coil 12b = 1 μH.

[0039]

According to the present invention, since the first antenna conductor and the second antenna conductor are connected in the first frequency band, the effective length of the first antenna conductor becomes longer. The sensitivity is improved.

The first coil has an inductance value for attenuating the reception signal in the second frequency band, and the connection length between the feeding point of the first antenna conductor and one end of the first coil is determined by the first coil. Since the received signal in the second frequency band is shortened so as not to be attenuated, the effective length of the first antenna conductor does not increase in the second frequency band, and the sensitivity in the second frequency band is hardly attenuated.

Further, when using the reception signal of the first antenna conductor in the first frequency band, the conductor length of the second antenna conductor can be used, so that the area occupied by the first antenna conductor can be reduced, and the size can be reduced. Can contribute to

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a typical example of a vehicle antenna according to the present invention.

FIG. 2 is a configuration diagram of a conventional example.

FIG. 3 is a configuration diagram of another example of the vehicle antenna of the present invention which is different from FIG.

FIG. 4 is a configuration diagram of an example of a vehicle antenna of the present invention of another type different from FIGS. 1 and 3;

FIG. 5 is a configuration diagram of another example of the vehicle antenna of the present invention which is different from FIGS. 1, 3 and 4;

FIG. 6 is a diagram showing sensitivity-reception frequency characteristics of FM broadcast bands in Examples 1 to 6;

FIG. 7 is a sensitivity-reception frequency characteristic diagram of an AM broadcast band of Example 7;

FIG. 8 is a sensitivity-reception frequency characteristic diagram of an AM broadcast band in Example 6;

[Explanation of symbols]

AT ₁ : first antenna conductor AT ₂ : second antenna conductor L ₁ : first coil L ₂ : second coil 1 b: rear right side window glass plate 4 a: first feeding point 4 b: second Feeding point 6: First connection line 8: Second connection line 9: Circuit 10: Coaxial cable 20: Receiver 22: Heater line 25a, 25b: Bus bar 29: Choke coil 30: DC power supply 21: Noise cut Capacitors 12a, 12b: high-frequency choke coil 41: DC blocking capacitor

Claims (4)

[Claims] 1. A vehicle antenna for receiving a first frequency band and a second frequency band higher in frequency than the first frequency band, comprising: a first antenna conductor, a second antenna conductor, and a second antenna. One coil is provided in the vehicle, the power supply point of the first antenna conductor is connected to one end of the first coil, the power supply point of the second antenna conductor is connected to the other end of the first coil, The first coil has an inductance value such that the impedance becomes high in the second frequency band, and the length of the connection line connecting the feeding point of the first antenna conductor and one end of the first coil is set to the first length. A receiving signal in a second frequency band received by the antenna conductor is shortened so as not to be attenuated, and a received signal at a feeding point of the first antenna conductor is input to a receiver. 2. A vehicular antenna for receiving a first frequency band and a second frequency band higher in frequency than the first frequency band, comprising: a first antenna conductor, a second antenna conductor, and a second antenna. A first coil is provided in the vehicle, a feed point of the first antenna conductor is connected to one end of the first coil, and the other end of the first coil is connected to one end of the second coil; The other end of the coil and the feeding point of the second antenna conductor are connected, and both the first coil and the second coil have an inductance value that becomes high impedance in the second frequency band. The length of the connection line connecting the feeding point of the antenna conductor and one end of the first coil is shortened so as not to attenuate the reception signal of the second frequency band received by the first antenna conductor. Received signal at feed point of antenna conductor and second antenna Vehicle antenna to input and select the stronger of the received signal feed points of the body to a receiver. 3. The vehicle antenna according to claim 1, wherein a length of a connection line connecting a feed point of the first antenna conductor and one end of the first coil is 40 cm or less. 4. The vehicle antenna according to claim 1, wherein the first antenna conductor is provided on the rear left side window glass plate, and the second antenna conductor is provided on the rear right side window glass plate.